Spring 2012 Jose E SchuttAine Electrical amp Computer Engineering University of Illinois jesaillinoisedu Signal Integrity Crosstalk Dispersion Attenuation Reflection Distortion Loss ID: 1030889
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1. ECE 598 JS Lecture - 05Coupled LinesSpring 2012Jose E. Schutt-AineElectrical & Computer EngineeringUniversity of Illinoisjesa@illinois.edu
2. Signal IntegrityCrosstalk Dispersion AttenuationReflection Distortion LossDelta I Noise Ground Bounce RadiationCrosstalk Noise
3. TEM PROPAGATION
4. Telegrapher’s EquationsL: Inductance per unit length.C: Capacitance per unit length.
5. Crosstalk noise depends on termination
6. tr = 1 nstr = 7 nsCrosstalk depends on signal rise time
7. tr = 1 nstr = 7 nsCrosstalk depends on signal rise time
8. Coupled Transmission Lines
9. Telegraphers Equations for Coupled Transmission LinesMaxwellian Form
10. Telegraphers Equations for Coupled Transmission LinesPhysical form
11. Relations Between Physical and Maxwellian Parameters(symmetric lines)L11 = L22 = LsL12 = L21 = LmC11 = C22 = Cs+CmC12 = C21 = - Cm
12. Add voltage and current equationsVe : Even mode voltageIe : Even mode currentImpedancevelocityEven Mode
13. Subtract voltage and current equationsVd : Odd mode voltageId : Odd mode currentImpedancevelocityOdd Mode
14. Mode Excitation
15. PHYSICAL SIGNIFICANCE OF EVEN- AND ODD-MODE IMPEDANCES* Ze and Zd are the wave resistance seen by the even and odd mode travelling signals respectively.* The impedance of each line is no longer described by a single characteristic impedance; instead, we have
16. Even-Mode Impedance: ZeImpedance seen by wave propagating through the coupled-line system when excitation is symmetric (1, 1).Odd-Mode Impedance: ZdImpedance seen by wave propagating through the coupled-line system when excitation is anti-symmetric (1, -1).Common-Mode Impedance: Zc = 0.5ZeImpedance seen by a pair of line and a common return by a common signal.Differential Impedance: Zdiff = 2ZdImpedance seen across a pair of lines by differential mode signal.Definitions
17. EVEN AND ODD-MODE IMPEDANCESZ11, Z22 : Self ImpedancesZ12, Z21 : Mutual ImpedancesFor symmetrical lines,Z11 = Z22 and Z12 = Z21
18. Coupled LinesLine SpaceModal Space
19. EXAMPLE(Microstrip)er = 4.3Zs = 56.4 WSingle LineDielectric height = 6 milsWidth = 8 milser = 4.3Coupled LinesHeight = 6 milsWidth = 8 milsSpacing = 12 milsZe = 68.1 W Zd = 40.8 WZ11 = 54.4 W Z12 = 13.6 W
20. Even Mode
21. Odd Mode
22. EXTRACT INDUCTANCE AND CAPACITANCE COEFFICIENTS
23. Measured even-mode impedance
24. Measured odd-mode impedance
25. Measured even-mode velocity
26. Measured odd-mode velocity
27. Measured mutual inductance
28. Measured mutual capacitance
29. Even & Odd Mode Impedances
30. Microstrip : Inhomogeneous structure, odd and even-mode velocities must have different values.Stripline : Homogeneous configuration, odd and even-mode velocities have approximately the same values.Modal Velocities in Stripline and Microstrip
31. Microstrip vs StriplineMicrostrip (h =8 mils)w = 8 milser = 4.32Ls = 377 nH/mCs = 82 pF/mLm = 131 nH/mCm = 23 pF/mve = 0.155 m/nsvd = 0.178 m/nsStripline (h =16 mils)w = 8 milser = 4.32Ls = 466 nH/mCs = 86 pF/mLm = 109 nH/mCm = 26 pF/mve = 0.142 m/nsvd = 0.142 m/ns
32. Microstrip vs StriplineSense line response at near endProbe
33. General Solution for Voltages
34. General Solution for Currents
35. Coupling of Modes (asymmetric load)
36. Coupling of Modes (symmetric load)
37.